Thank you Per This stage involves a lot of swarf. I did consider using a hole saw to remove the bulk of the material but it's not easy to maintain the centre on square work.

Next up was the hole through the cam carrier. I did consider setting the halves up in the mill and using a 3mm ball nose mill to cut a 'pilot' bore to stop things wandering but decided to try the easy way first. I set in up in the 4 jaw chuck and pilot drilled 2.5mm with a long series drill followed by 9.8mm and a 10mm reamer. The hole looked to be central at the far end

I then made a centring plug for the next operations and went back to milling mode on the crankcase. This was clamped to the table and aligned with stops set on the X axis so I could work between the two bores. As the wall is quite thin at that point I ran the centre dill right through to act as a pilot. This was then opened out to 15.5mm (my largest MK2 drill) ready for boring.

The two holes were then opened out to 23mm with the boring head using a brazed carbide tool at 560 rpm and 0.6mm depth of cut.

I then set up the cylinder block using two 6mm square tool blanks as parallels to allow through boring. This was pilot drilled 4mm (the smallest drill that was long enough) and opened out to 15.5mm. The mill was struggling a little at the lowest speed but got through. I was using the quill feed for boring and had to extend the sleeve on the drawbar to be able to use the full travel (quill stroke 50mm, cylinder block 48mm). Luckily I had a suitable sleeve from my governor experiments and didn't have to resurrect the minilathe to make one. I used the same speed and feed as before but with a longer boring tool. It seemed to chatter mid bore until I realised that that was the point where I changed my grip on the handle and must have changed the feed rate If I used both hands I could keep it steady.

Thank you both Alex, it is planned to be splash lubricated with a side oil reservoir like the single. This time the reservoir will be under the camshaft. There is space for an oil pump but I don't think it will be needed. I have used a pumped system on my diesel but the loads there will be higher.

I finished the other bore and then set up the rotary table to round off the ends of the cylinder block. I used a 14mm end mill at 560 rpm in 10mm steps with 0.5mm depth of cut. The finishing cut was 0.2mm deep. There are chatter marks but they can be removed with light filling.

Thank you all for your interest I can afford the better machines, but not the space to install them

The next step was to drill and ream for the cam follower guides in the cam carrier. As this requires 10mm holes on 10mm centres there is not much left in the middle but it works I then drilled the fixing holes for the cam carrier and cylinder block and spotted them through onto the crankcase. Problem 6 of the holes lined up nicely, two were more than a mm out They will have to be tapped out M5 plugged and redrilled

The next step was to cut two connecting rod blanks from a piece of 60mm x 10mm aluminium bar (the new bandsaw is wonderful). The ends were marked out and the center holes as well as the big end fixings were drilled. The next steps require going back to lathe mode.

I then moved on to the timing gear cover. This was to be cut from a piece of scrap 15mm aluminium which unfortunately had an M5 hole in just the wrong place. I used a 6mm endmill to move it over slightly. The final size will be 10mm but I wanted to reduce the chance of the next operation being deflected. This was roughed out with the bandsaw (it's just possible to cut 115mm in a 105mm saw ) along with the backplate. The edges were trued up and the two pieces were sandwiched together for drilling.

The two outer 6mm holes do not go right through. The inner one was opened out further with a 8mm end mill to reduce the chance of deflection before drilling 9.8mm and reaming 10mm. I used a previously made 10mm dia. 6mm bore sleeve to align the two pieces and fitted one of the outer hole over the 6mm spigot in the RT. The fixing bolt went through the hole in the sleeve. I then started to round the first end in a similar way to the cylinder block.